TDI is based on the concept of accumulating multiple exposures of the
same (moving) object, effectively increasing the integration time available
to collect incident light. The object motion must be synchronized with
the exposures to ensure a crisp image. The TDI method of line scanning
provides dramatically increased responsivity compared to other video scanning
methods and permits much greater scanning speeds in low light, or allows
reduced lighting levels (and costs) at conventional speeds.

BenefitsMore speed: With more effective integration time, you can increase
the speed of the target object or inspection web.Less light, less expense: Instead of high-powered, high-cost,
high-temperature halogen lighting with DC power, you can use high-frequency
AC or even LED lighting, profoundly lowering your system maintenance costs.
TDI operation effectively averages out fluctuations in light intensity
to represent a DC light source. This factor alone can justify the increased
cost of a TDI sensor versus the cost of using DC regulated light source
and a line scan image sensor.